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Gromochytrium mamkaevae gen. & sp. nov. and two new orders: Gromochytriales and Mesochytriales (Chytridiomycetes).

Karpov SA, Kobseva AA, Mamkaeva MA, Mamkaeva KA, Mikhailov KV, Mirzaeva GS, Aleoshin VV - Persoonia (2014)

Bottom Line: During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny.Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets.An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae.

View Article: PubMed Central - PubMed

Affiliation: Zoological Institute, Russian Academy of Sciences, St. Petersburg 198904, Russian Federation; ; Biological Faculty, St. Petersburg State University, St. Petersburg 198904, Russian Federation.

ABSTRACT
During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU - a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.

No MeSH data available.


Related in: MedlinePlus

General scheme of zoospore structure. — a. Gromochytrium mamkaevae (x-51 CALU); b. Mesochytrium penetrans (x-10 CALU). Arrows show the spiral fiber in flagellar transition zone (b: after Karpov et al. (2010) with modified abbreviations).— Abbreviations: ar = anterior microtubular root; br = bridge between kinetosome and centriole; c = centriole; d = kinetosome diaphragm; db = dense bodies; er = endoplasmic reticulum; fc = fenestrated cisterna; gf = girdle fiber; k = kinetosome; l = lipid globule; m = mitochondrion; mb = microbody; n = nucleus; pr = posterior microtubular root; ps = pseudopodia; rc = ribosomal core; s = spur; tf = transitional fibers (props); v = vacuole; ve = veil; vz = vesicular zone.
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Figure 5: General scheme of zoospore structure. — a. Gromochytrium mamkaevae (x-51 CALU); b. Mesochytrium penetrans (x-10 CALU). Arrows show the spiral fiber in flagellar transition zone (b: after Karpov et al. (2010) with modified abbreviations).— Abbreviations: ar = anterior microtubular root; br = bridge between kinetosome and centriole; c = centriole; d = kinetosome diaphragm; db = dense bodies; er = endoplasmic reticulum; fc = fenestrated cisterna; gf = girdle fiber; k = kinetosome; l = lipid globule; m = mitochondrion; mb = microbody; n = nucleus; pr = posterior microtubular root; ps = pseudopodia; rc = ribosomal core; s = spur; tf = transitional fibers (props); v = vacuole; ve = veil; vz = vesicular zone.

Mentions: The structure of the flagellar apparatus was investigated with serial sections of six released zoospores. The kinetosome and centriole are embedded in the ribosomal core (Fig. 3d, e, 4). The kinetosome is c. 400 nm long and composed of microtubular doublets (not triplets) with developed transitional fibers (props) (Fig. 4b–d). The flagellar transition zone is simple without transversal plate, but with a slightly inward curved diaphragm at the distal end of kinetosome (Fig. 4g). Two thin lines parallel to the peripheral microtubular doublets are present above the diaphragm, and seem to correspond to the spiral fiber, or cylinder (Fig. 4g). The centriole is about 100 nm long and lies at an angle of c. 30° to the kinetosome (Fig. 3e, 4b, c, e, f). The kinetosome is connected to the centriole by a broad fibrillar bridge composed of at least three thick connectors (Fig. 4d). The longest middle connector passes through the bottom of kinetosome to the side of centriole. The structure of interconnecting bridge seems to be an unstable character. The bridge looks rather broad and prominent, connecting the sides of kinetosome and centriole at the longitudinal sections (Fig 4e, f), but it is not visible at the corresponding transverse sections (Fig. 4b–d). Approximately 1/3 of all serial sections had the broad bridge connecting the sides of kinetosome and centriole and in 2/3 of the series the bridge connects the bottom of kinetosome to the side of centriole. The diagram (Fig. 5a) shows the more common state.


Gromochytrium mamkaevae gen. & sp. nov. and two new orders: Gromochytriales and Mesochytriales (Chytridiomycetes).

Karpov SA, Kobseva AA, Mamkaeva MA, Mamkaeva KA, Mikhailov KV, Mirzaeva GS, Aleoshin VV - Persoonia (2014)

General scheme of zoospore structure. — a. Gromochytrium mamkaevae (x-51 CALU); b. Mesochytrium penetrans (x-10 CALU). Arrows show the spiral fiber in flagellar transition zone (b: after Karpov et al. (2010) with modified abbreviations).— Abbreviations: ar = anterior microtubular root; br = bridge between kinetosome and centriole; c = centriole; d = kinetosome diaphragm; db = dense bodies; er = endoplasmic reticulum; fc = fenestrated cisterna; gf = girdle fiber; k = kinetosome; l = lipid globule; m = mitochondrion; mb = microbody; n = nucleus; pr = posterior microtubular root; ps = pseudopodia; rc = ribosomal core; s = spur; tf = transitional fibers (props); v = vacuole; ve = veil; vz = vesicular zone.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4150072&req=5

Figure 5: General scheme of zoospore structure. — a. Gromochytrium mamkaevae (x-51 CALU); b. Mesochytrium penetrans (x-10 CALU). Arrows show the spiral fiber in flagellar transition zone (b: after Karpov et al. (2010) with modified abbreviations).— Abbreviations: ar = anterior microtubular root; br = bridge between kinetosome and centriole; c = centriole; d = kinetosome diaphragm; db = dense bodies; er = endoplasmic reticulum; fc = fenestrated cisterna; gf = girdle fiber; k = kinetosome; l = lipid globule; m = mitochondrion; mb = microbody; n = nucleus; pr = posterior microtubular root; ps = pseudopodia; rc = ribosomal core; s = spur; tf = transitional fibers (props); v = vacuole; ve = veil; vz = vesicular zone.
Mentions: The structure of the flagellar apparatus was investigated with serial sections of six released zoospores. The kinetosome and centriole are embedded in the ribosomal core (Fig. 3d, e, 4). The kinetosome is c. 400 nm long and composed of microtubular doublets (not triplets) with developed transitional fibers (props) (Fig. 4b–d). The flagellar transition zone is simple without transversal plate, but with a slightly inward curved diaphragm at the distal end of kinetosome (Fig. 4g). Two thin lines parallel to the peripheral microtubular doublets are present above the diaphragm, and seem to correspond to the spiral fiber, or cylinder (Fig. 4g). The centriole is about 100 nm long and lies at an angle of c. 30° to the kinetosome (Fig. 3e, 4b, c, e, f). The kinetosome is connected to the centriole by a broad fibrillar bridge composed of at least three thick connectors (Fig. 4d). The longest middle connector passes through the bottom of kinetosome to the side of centriole. The structure of interconnecting bridge seems to be an unstable character. The bridge looks rather broad and prominent, connecting the sides of kinetosome and centriole at the longitudinal sections (Fig 4e, f), but it is not visible at the corresponding transverse sections (Fig. 4b–d). Approximately 1/3 of all serial sections had the broad bridge connecting the sides of kinetosome and centriole and in 2/3 of the series the bridge connects the bottom of kinetosome to the side of centriole. The diagram (Fig. 5a) shows the more common state.

Bottom Line: During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny.Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets.An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae.

View Article: PubMed Central - PubMed

Affiliation: Zoological Institute, Russian Academy of Sciences, St. Petersburg 198904, Russian Federation; ; Biological Faculty, St. Petersburg State University, St. Petersburg 198904, Russian Federation.

ABSTRACT
During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU - a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.

No MeSH data available.


Related in: MedlinePlus